CODEWITHSUNDEEP
ruby-on-railsrubyactiverecordruby-on-rails-4
onetwopunch
onetwopunch

Reputation: 3329

How to make active record initialize with params in Rails 4?

I am using Ruby on Rails 4 and I have this User model:

require 'uuid'
UUID.state_file = false
UUID.generator.next_sequence

class User < ActiveRecord::Base
   attr_accessor :email, :password
   has_many :entries

   after_initialize do |user|
       user.entry_hash = UUID.new.generate
   end

end

Which is based on the following DB migration:

class CreateUsers < ActiveRecord::Migration

def change
    create_table :users do |t|
        t.string "email"
        t.string "password"
        t.string "entry_hash"
      t.timestamps
    end

  end
end

I want to automatically generate a uuid as a hash associated with that User.

Using the rails console to create a new User, I do the following:

1) I use create a User with an email and password:

irb(main):001:0> u = User.create(:email=>'[email protected]', :password=>'myPass')
   (0.1ms)  BEGIN
  SQL (0.6ms)  INSERT INTO `users` (`created_at`, `entry_hash`, `updated_at`) VALUES ('2013-12-07 22:32:28', '60744ec0-41bd-0131-fde8-3c07542e5dcb', '2013-12-07 22:32:28')
   (3.7ms)  COMMIT
=> #<User id: 2, email: nil, password: nil, entry_hash: "60744ec0-41bd-0131-fde8-3c07542e5dcb", created_at: "2013-12-07 22:32:28", updated_at: "2013-12-07 22:32:28">

2) But this is weird. If you look at the SQL, it doesn't insert anything but the entry_hash, and the output object shows email and password as nil. However, when I try to access those properties, I get the ones I put.

irb(main):002:0> u.email
=> "[email protected]"
irb(main):003:0> u.id
=> 2
irb(main):004:0> u.password
=> "myPass"
irb(main):005:0> u.entry_hash
=> "60744ec0-41bd-0131-fde8-3c07542e5dcb"

I am very new to Ruby on Rails and I know some magical stuff goes on in the background, but can someone enlighten me as to whats going on here? I just want to create an object with parameters.

Cheers

UPDATE: I fixed the problem I was having by removing the attr_accessor line. Anyone know why that made it work?

Upvotes: 2

Views: 1103

Answers (1)

givanse
givanse

Reputation: 14943

attr_accessor

  • Can be used for values you don't want to store in the database directly and that will only exist for the life of the object (e.g. passwords).

  • Is used when you do not have a column in your database, but still want to show a field in your forms. This field is a “virtual attribute” in a Rails model.

The method create creates the row in the database and also returns the ruby object. That is why accessing the fields through the variable u worked, it is alive while the console is open. However, nothing made it to the database.

Upvotes: 3

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